The overall objective of the present proposal is to investigate the physiologic concomitants of the attentive processes operative during episodes of spontaneous mother-infant interaction. We seek to identify the extent to which each individual's response to the other's social signals affects the developing mother-infant communication. Several studies of mother-infant interaction have found that maternal behavioral response affects the infant developmentally through contingency of maternal response to the infant's signals (e.g., Ainsworth & Bell, 1973). It has also been reported that mothers who were behaviorally less sensitive to their infant's signals during a feeding session at 9 months had earlier shown an attentional deficit (indexed by physiological response) when exposed to infant signals (Donovan & Leavitt, 1977). The proposed studies are designed to relate both behavioral and physiologic data recorded during interaction to specific aspects of the infant's later social and cognitive development. In the proposed studies, mother-infant dyads will first be observed in a feeding session to determine whether specific patterns of interaction are correlated with characteristic physiologic response of either mother or infant during interaction. In the second phase, we will assess the relationship between mother and infant's differential responding (behavioral and physiologic) and the infant's subsequent cognitive and social development. Infants will be tested on an object permanence task (Uzgiris & Hunt, 1975) and will be observed for attachment behaviors in the strange-situation (Ainsworth & Wittig, 1969). The general hypothesis is that increased maternal sensitivity, behavioral and physiological, is positively correlated with more advanced development.